Appendicitis is a serious medical condition in which the appendix — a small, finger-shaped organ attached to your large intestine — becomes swollen and inflamed. It’s not always clear what causes appendicitis. Often, appendicitis is probably the result of an obstruction of the area inside the appendix called the appendiceal lumen (the interior of the tube of the appendix), or appendix lumen. (1)
There are numerous issues that can cause appendix luminal blockage, including:
- Appendicoliths or fecaliths, which are calcified fecal deposits also known as “appendix stones” (this is more common in children than adults) (2)
- Intestinal worms or parasites, including pinworm (Enterobius vermicularis)
- Irritation and ulcers in the gastrointestinal (GI) tract resulting from long-lasting disorders, such as Crohn’s disease or ulcerative colitis
- Abdominal injury or trauma
- Enlarged lymph tissue of the wall of the appendix, which is typically the result of infections in the GI tract
- Benign or malignant tumors
- Various foreign objects, such as stones, bullets, air-gun pellets, and pins (3)
Sometimes appendicitis is due to a viral, bacterial, or fungal infection that has spread to the appendix. (4) Possible causes of infection include, but are not limited to:
- E. coli, which are bacteria found in the environment, foods, and intestines of animals. Most strains of E. coli are harmless, but others can cause illness. (5)
- Pseudomonas bacteria, which are found in soil and water and moist areas such as sinks and toilets (6)
- Bacteroides, bacteria that already inhabit the digestive tract of humans (7)
- Adenovirus, a very common virus spread through contact or through the air that can cause cold-like symptoms as well as bladder and other infections. (8)
- Salmonella, a foodborne bacteria that typically causes gastrointestinal upset (diarrhea, nausea, and vomiting) but can have serious complications
- Shigella bacteria, germs that are very contagious and typically result in diarrheal illness that usually lasts no more than a week. (9)
- Measles, a highly contagious virus spread through the air and contact. Vaccination protects most of the population, but there are outbreaks in which unvaccinated people are susceptible (10)
- The fungal infections mucormycosis (a rare but serious mold infection caused by environmental molds) (11) and histoplasmosis; most people who breathe in these spores won’t get sick or will have mild symptoms, but infection can become severe in people with weakened immune systems (11)
Your appendix is home to many beneficial bacteria. In fact, recent research has focused on the role the appendix might play in immune function. Long considered to be a vestigial organ without much purpose, the appendix, some experts now think, is involved in both encouraging and protecting the growth of beneficial gut bacteria: When certain diseases destroy beneficial gut bacteria in the GI tract, the appendix helps to recolonize the gut after infection. (12)
But when the organ becomes infected or obstructed, bacteria in the appendix multiply rapidly, causing your appendix to swell and fill with pus — a thick liquid containing bacteria, tissue cells, inflammatory debris, and dead infection-fighting white blood cells.
The Possible Complications of Appendicitis
If left untreated, appendicitis will often get progressively worse as the inflammation leads to further complications.
Sepsis Symptoms and Diagnosis
Pressure within the appendix will increase, limiting the amount of blood flowing through the walls of the appendix, where the tissue then becomes starved of blood and starts to die.
Eventually, the appendix will rupture, leaking its contents throughout the abdomen. In some cases, abscesses (pockets of pus) may form on the ruptured appendix; if the abscesses tear, they can infect the rest of the abdomen, which is extremely dangerous and potentially fatal.
In other cases, the ruptured appendix may cause the peritoneum — the silk-like membrane that lines the abdominal cavity — to become infected, a condition called peritonitis. This serious complication can then lead to a potentially fatal blood infection called sepsis.
What Are the Risk Factors for Appendicitis?
There’s no way to predict who will get appendicitis, but scientists have uncovered several risk factors for the condition. These include:
- Being a teenager or in your twenties; (13) most cases of appendicitis occur in this age group
- Having a long-lasting inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis
- Studies have suggested that family history plays a role; a study published in the Western Journal of Emergency Medicine found that among adults at an emergency room who presented with appendicitis, those with a known family history were more likely to have the condition (14)
And a study published in the Journal of Pediatric Surgery found that “heredity is a significant factor” in children who have appendicitis. (15)
There’s also a link between air pollution — in particular, high levels of ozone — and appendicitis. Scientists aren’t sure why air pollution is associated with an increased risk of appendicitis, but it may be that high levels of ozone increase intestinal inflammation or increase susceptibility to bacterial and viral infections. (16)
Studies suggest that people get appendicitis more during the summer than at other times of the year. It’s not clear why, but a review of over 40 years of research, published in Annals of Medical and Health Sciences Research, concludes that it’s likely due to a combination of increased exposure to air pollution and more GI infections during summer months. (17)